The present invention relates to a shellfish and algae inhibiting composition which is coated on a ship bottom, a fishing net, apparatus, in sea such as a buoy for wave generator, a construction in water such as a dam apparatus, a waterway for cooling water used in a condenser of a heat power plant or in a heat-exchanger for petrochemical plants.
It has been known that various shellfish and algae such as Balanus, Ostrea, Mytilus, Hydrozoa, Styela, Bugula, Ulva, Enteromorpha, Ectocarpus, etc.. have been bred on the surfaces in water such as the ship bottom, the apparatus in water, the construction in water, the waterway for cooling water and the like.
These shellfish and algae cause the increase of flow resistance and the decrease of heat conductivity to disadvantageously decrease the functions of the apparatus.
For example, taking the ship, the decrease of the speed and the excess consumption of the fuel are caused. Moreover, in order to clean the ship bottom, the loss for the suspension of the ship service is caused and the cost for the cleaning is needed. These are remarkable economical loss.
In the constractions in water, the handling trouble is caused.
In the waterway for cooling water used in the condenser or the heat exchanger, the rate of water supply is decreased to decrease the cooling coefficient, and the function of the condenser or the heat exchanger is damaged by shellfish or algae mass which are peeled off from the wall of the waterway. These are also remarkable economical loss.
In order to prevent such trouble caused by the breeding and the adhesion of shellfish and algae in sea water or fresh water, it has been proposed to use paints containing a heavy metal compound such as copper oxides, mercury oxides; an organo-tin oxide; an organic chlorine-containing compound and an organic sulfur-containing compound, or an arsenic compound such as phenarsazine chloride etc..
In the waterway for the cooling water, chlorine or formaline is directly added in the water to prevent the breeding and the adhesion of shellfish and algae.
However, the inhibiting compositions containing the heavy metal compound such as copper oxides and mercury oxides have low stability in a storage because the heavy metal compound is reactive to the resin component in the composition.
In the polluted sea such as harbor to which industrial discharged water is flowed, hydrogen sulfide is generated by microorganism in the polluted sea and the heavy metal compound is discolored and deteriorated to lose the effect.
The copper compounds and the mercury compounds are effective against shellfish such as Balanus, Ostrea, Mytilus, Hydrozoa, Styela, Bugula, etc., however, they are not effective against algae.
When the inhibiting composition is coated on a substrate made of light metal such as aluminum and aluminum-magnesium, the heavy metal such as copper and mercury is deposited on the substrate to electrochemically accelerate the corrosion of the substrate. This is the other disadvantage.
The inhibiting compositions containing the organo-tin compound such as tributyl tin oxide have inferior effect to those of the inhibiting compositions containing the copper compound or the mercury compound, and also they are expensive. When a large amount of the organo-tin compound is mixed, the characteristics of the coated film is deteriorated and bad smell is caused in the handling.
The inhibiting compositions containing the organic chlorine-containing compound or the organic sulfur-containing compound have inferior effects comparing with the other inhibiting compositions. For example, even though they are effective for Bugula, they are not effective for Balanus. They are only effective for certain shellfish or algae whereby it is difficult to use them in practical applications.
The inhibiting composition containing phenarsazine chloride has been used. However phenarsazine chloride is toxic to human body, and stimulates mucous membrane whereby the preparation of the composition and the coating operation are not easy. When chlorine or formaline is added to water in the waterway for the cooling water, the cooling apparatus is corroded and the effect for inhibiting the adhesion of shellfish and algae is not remarkable.
These conventional active ingredients are toxic to human body and fish, whereby the application is limited.
In the specification, the composition for inhibiting an adhesion of shellfish and algae is referred as the shellfish-algae inhibiting composition.